The invention relates to the field of cable installation. More particularly, the invention relates to the field of the installation of suspended cable such as fiber optic cable suspended in the air via poles which are anchored to the ground.
In the field of cable installation, cables are often suspended overhead on utility poles. Though telegraph cables were the first cables to be suspended on poles in the Nineteenth Century after buried cable proved faulty, today many cables are suspended. Suspending cables overhead is an inexpensive way to both insulate the cables from the ground and to keep them out of the way of people, vehicles, structures, paths, roads, and the like. Power cables used for distribution and subtransmission lines are commonly suspended from utility poles. Larger towers, in place of poles, are often used for power transmission lines. In the field of telecommunications, it is common for various types of cable to be suspended on poles or other structures and the telecommunication cables may use the same poles or structures as power lines. For instance, telephone cable may be suspended on poles for the delivery of commercial telephone service to residences and businesses. Likewise, coaxial cable may be suspended for the delivery of cable television services. Coaxial and telephone cables may also be suspended on poles in order to deliver internet and other data communication services. Similarly, optical cables such as fiber optic cable or other communication cables such as Category 5 or Category 6 cables may be suspended. It is also common for speaker cables, public address cables, and the like to be suspended in certain applications.
Though the suspension of cables on poles and other overhead structures has many benefits, there are also disadvantages related to installation. For instance, because of the height of the poles or other structures, ladders, lifts, or other elevation equipment must be utilized in order to reach the cables and their various attachments. As cables can be strung for runs of thousands of feet, and indeed miles, the task of suspending cables from pole to pole can be labor intensive. Thus, there is a need in the art for a device that improves the process of suspending cables.
The task of suspending cables is exacerbated when the cables are fragile. Whereas a copper electrical cable may withstand significant pulling, bending, and wear during a process of suspension, fragile cables such as fiber optic cables may easily become damaged during overhead installation. This damage can occur when too much pressure or stress is applied to a cable. This damage can occur when a cable bends too sharply around a corner. This damage can occur when the cable gets caught around the axle of a pulley in prior sheave art. The damage can also occur when various parts, such as latches, of prior art sheaves become detached such that the cable becomes removed from the prior art sheaves. This damage can also occur because prior art sheaves have no way to retain the cable as it tightens or slackens while it is being pulled. Damage may also occur when splices in cable become lodged in the sheave causing undue strain or stress on the cable such as when an operator does not stop pulling the cable in time to prevent damage to the cable. Thus, there is a need in the art for a device that enables the safe installation of fragile cables such as fiber optic cables.
Damage to fragile cables can also occur when the profile or “floor” of a sheave is not uniformly round. It is common in the art of sheave and pulley design to have the wheel of the sheave or pulley have spokes supporting and distancing the “floor” of the sheave from the hub or axle of the wheel, much like a bicycle wheel. One problem in the art occurs when sheaves are made of plastic. When a plastic sheave is formed, it typically shrinks as it is curing. Thin parts will set and cure quicker than thick parts and this disparity can cause thin portions of the wheel to cure quicker than thicker portions. When portions of the plastic floor are not supported by the spokes, the floor tends to shrink towards the hub whereas the portions directly supported by the spokes shrink mush less and remain, relatively in place. This shrinkage differential can cause the floor of the pulley wheel to have peaks and valleys. These peaks and valleys are more pronounced as the wheel diameter is increased in size. Peaks and valleys in the wheel act to defeat the benefits of a wheel in the first place and importantly can damage fragile fiber optic cable. Thus, there is a need in the art for a plastic sheave wheel design that minimizes or eliminates peaks and valleys, especially in larger sheave wheels.
Further, as cables often carry electrical current, there is a risk that those who install such cables or who operate and install other cables which are close to power cables may become electrocuted. Thus, there is a need for a dialectically strong assembly due to the potential proximity to power cables.
Further, as cables are also suspended or otherwise installed in buildings, there is also a need in the art to allow cables, such as fragile fiber optic cables, to be quickly, easily, and safely installed around corners so that the cables do not become damaged. There is also a need in the art for a sheave that is lightweight and efficient to manufacture.